1. Technical Field
The present invention relates to a light emitting diode, and more particularly, to a light emitting diode having improved internal quantum efficiency using a magnetic field.
2. Description of the Related Art
A light emitting diode (LED) is a kind of p-n junction diode and is a semiconductor device using electroluminescence, in which monochromatic light is emitted when forward voltage is applied to the semiconductor device.
The light emitting diode is operated to generate light when voltage is applied between two electrodes, that is, a cathode and an anode, to supply electric current. In particular, an n-type semiconductor layer and a p-type semiconductor layer are placed on upper and lower sides of an active layer having a multi-quantum well structure, respectively. The n-type semiconductor layer supplies electrons to the active layer, while the p-type semiconductor layer supplies holes to the active layer. Electrons and holes introduced into the multi-quantum well structure are defined within quantum well layers by quantum confinement, and recombined with each other, thereby generating light.
Nitride compound semiconductors, represented by gallium nitride (GaN), have received much attention in the field of high power electronic devices including LEDs, since they have high thermal stability and a wide range of band-gap from 0.8 eV to 6.2 eV.
In a GaN-based light emitting diode, use of a magnetic field has been proposed in order to improve quantum efficiency.
However, the active layer is not sufficiently thick for linear motion of charge carriers to be converted into cyclotron motion by an external magnetic field.
In order to address this problem, a magnetic field is applied to the active layer through a magnetic layer grown directly in the light emitting diode.
However, a non-uniform magnetic field applied by the magnetic layer is present over a very wide range and thus does not have a significant influence on the motion of charge carriers.